1. Field of the Invention:
This invention relates to a mechanical transducer and, in particular, to such a mechanical device which is particularly adapted for use as the actuator for a damper of a ventilation system.
2. Description of the Prior Art:
Multiple zone air conditioning systems typically have air heating and air cooling equipment in plenum chambers of air circulating systems. The air circulating systems have a blower and duct and damper means whereby a controlled circulation of air to the individual zones of multiple zone systems can be achieved. The dampers of such systems generally have a baffle member that is driven between open and closed positions by a reversible electrical motor which is controlled by suitable thermostat circuits.
Various mechanical drives have been employed for the baffle member of the dampers, including lead screw and traveling nut members such as those shown in the following U.S. Pat. Nos. 2,783,702; 2,837,991; and 3,363,536. Typically, the lead screw and traveling nut member utilized in such damper construction are integral components of the damper construction rather than a modular unit which can be removably attached to the damper. In such construction, the lead screw of the traveling nut member is not protected from the environment but, instead, is open and exposed in the damper unit. The threads of this member can, therefore, become clogged with dirt and the like, increasing the resistance to the driver unit and requiring periodic maintenance.
The electronic control circuits for the actuator drive motor are frequently contained in an electrical control box which is remote from the drive motor and its mechanical linkage to the baffle member of the damper. This complicates the installation and repair of the thermostatic control units and complicates the feedback system whereby the actuator motor can be proportionally controlled.
Accordingly, there is need for a simple modular unit for the control of the baffle member of a damper which is self-contained and includes the electronic circuit for the control of the actuator motor, the actuator motor and mechanical linkage therefor. Desirably, the components of such a modular unit should be contained in a housing while permitting facile access thereto for installation and servicing.